1. Field of the Invention
This invention relates to closures for paperboard cartons and more particularly to means for providing a tight seal in the closure to prevent the contents thereof from sifting out through the seams.
2. Description of the Prior Art
Paperboard cartons are an inexpensive and convenient method for storage, shipment and display of almost any type of article. Where the contents of the carton, however, are to be finely divided, such as powders, granulated materials, or any small particulate matter such as seeds, it is necessary that the end closures of the carton be tightly sealable. This seal is necessary not only to keep the contents from sifting out through the seams, but to prevent insects from attaining entry into the box. A common method of overcoming these problems is to provide the carton with a bag enclosure within the carton or a tight paper overwrap label over an unprinted paperboard package. This, of course, adds to the complexity of the equipment, the cost of the packaging, as well as the shipping weight.
Embossing the end flaps so that they lie in closer relationship is also common, as described in U.S. Pat. No. 3,003,677 which is assigned to the assignee of the present application. None of these solutions is entirely desirable nor completely satisfactory in its operation.